There is an increased necessity to remove fine particles and harmful substances contained in exhaust gases from boilers and the like in consideration of the adverse effect of them to the environment. In particular, regulations as to removal of fine particles (hereinafter, also called PM) exhausted from diesel engines tend to be made more strict in Europe and the United States as well as in Japan, and a honeycomb structural body is used as a collecting filter (hereinafter, also called DPF) to remove the PM.
In general, as shown in FIGS. 3(a) and 3(b), the honeycomb structural body used as the collecting filter and the like has such a structure that it includes a plurality of cells 23, which are partitioned by a porous partition wall 24 and act as fluid flow paths, and adjacent cells 23 are plugged at one ends opposite to each other so that the end surfaces of the cells 23 exhibit a checkered pattern. In the honeycomb structural body 21 having the above structure, a fluid to be treated flows into a cell 23 whose flow-in-hole side end surface 25 is not plugged, that is, a cell 23 whose end portion is plugged on a flow-out-hole side end surface 26 and is exhausted from an adjacent cell 23, that is, from the cell 23 whose end portion is plugged on the flow-in-hole side end surface 25 and whose flow-out-hole side end surface 26 is not plugged passing through the porous partition wall 24. At the time, the partition wall 24 acts as a filter, and when the honeycomb structural body is used as the DPF, soot and the like exhausted from diesel engines is trapped by the partition wall 24 and deposited on it.
The honeycomb structural body 21 used as described above has a problem in that a temperature is unevenly distributed in the honeycomb structural body 21 due to the arbitrary change of temperature of an exhaust gas and local heat generation and thus cracks and the like are made in the honeycomb structural body 21. In particular, when the honeycomb structural body 21 is used as the DPF, it must be regenerated by burning off accumulated carbon fine particles. At the time, the honeycomb structural body 21 is locally heated to a high temperature unevenly, from which a problem arises in that a regenerating efficiency is lowered and clacks are liable to be made due to a large amount of thermal stress.
To cope with the above problems, there are disclosed methods of joining segment-like honeycomb structural bodies (segments) obtained by dividing a honeycomb structural body by a joint material (refer to, for example, Patent Document 1).
When the segment-like honeycomb structural bodies are joined to each other by the joint material, the end surfaces of the respective honeycomb structural bodies are protected by a resin tape bonded onto them to prevent an extra joint material from protruding and entering into the openings of cells formed to the respective honeycomb structural bodies. Further, when silicon carbide (SiC) having a small coefficient of thermal expansion is used as the material of the honeycomb structural body, a manufacturing method of joining segment-like honeycomb structural bodies is also used.    Patent Document 1: Japanese Patent Publication No. 61-51240